Hereditary angioedema is a disease inherited as an autosomal dominant, characterized by abnormalities of a serum protein, the C1 esterase inhibitor. We showed that danazol corrected the condition in patients with low levels of the protein as well as in patients with protein which is present but not functonally active. Almost all of the patients receiving danazol develop near normal levels of C1 esterase inhibitor protein. Thus, the drug appears to induce gene synthesis of this protein and suggests that these patients have at least one gene capable of normal function. This tends to clarify the genetic basis of this disease and provides one of the first examples f correction of a genetic defect with drug therapy. Studies on the biochemical basis of this disorder as well as on various aspects of therapy continue. BIBLIOGRAPHIC REFERENCES: Gelfand, J.A., Sherins, R.J., Alling, D.W., and Frank, M.M.: Treatment of hereditary angioedema with danazol: Reversal of clinical and biochemical abnormalities. New Engl. J. Med. 295: 1444-1448, 1976. Reynolds, H.Y., Fulmer, J.D., Kazmierowski, J., Roberts, W.C., Frank, M.M., and Crystal, R.: Analysis of broncho-alveolar lavage fluid from patients with idiopathic pulmonary fibrosis and chronic hypersensitivity pneumonitis. J. Clin. Invest. 59: 165-175, 1977.